Hematopoietic factors in graft-versus-host reaction

Recombinant cytokines and hematopoietic growth factors in allogeneic and autologous bone marrow transplantation

Use of recombinant hematopoietic growth factors in the course of bone marrow transplantation has revolutionized this modality by significantly improving the safety of the procedure. It is anticipated that use of cytokines in combination and the introduction of newer agents will further reduce costs and improve antitumor responses as well.

Cytokine dysregulation in chronic graft versus host disease

Cytokines play a key role in the pathogenesis of chronic Graft versus Host Disease (cGVHD) and various studies have shown abberant production of cytokines by immune cells from GVHD patients. Based on these findings and others showing that high TNF levels precede the development of GVHD, we evaluated inflammatory cytokine levels following BMT and during the development of cGVHD. In this study, patients undergoing bone marrow transplantation (BMT) who consequently developed chronic GVHD were analyzed as to their cytokine production during cGVHD and this was correlated with their clinical manifestations. A positive correlation was found between the severity as well as the number of major clinical complications and high levels of inflammatory cytokines (IL-1 beta IL-6 and TNF alpha) compared to control patients or to normal donors. Patients undergoing BMT who did not develop GVHD, did not produce high levels of IL-1 beta IL-6 or TNF. High levels of cytokines may be used as a tool for assessing novel therapeutic modalities and response to GVHD treatment.

Thymus and T cells are not essential for rat leucopoiesis

It is generally held that T lymphocytes take part in the regulation of haemopoiesis. We have examined whether, in vivo, the influence of thymus of functional T cells is dispensable for the steady-state or accelerated formation of granulocytes (and in some experiments macrophages), utilizing a rat model. Untreated normal and athymic 'nude' rats had similar blood and marrow granulocyte counts and marrow proliferative activity. Bone marrow regeneration after two cytotoxic insults to the two kinds of rats gave no clues to an important regulatory role for thymic factors or T cells. Nor were such clues obtained in experiments where bone marrow cells from normal rats were cultured in vivo in diffusion chambers (DC), in either normal rats or rats undergoing a graft-versus-host (GvH) reaction (with supranormal serum levels of cytokines). On the other hand, when marrow cells from athymic rats were similarly cultured in DC, small but significant differences in leucopoiesis occurred between the three kinds of DC hosts: Marrow cells lacking functional T cells generated fewer proliferative granulocytes and had a lower proliferative activity when cultured in athymic than in normal hosts, whereas the proliferative granulocytes were most numerous in chambers carried by GvH rats. No differences were found for macrophages and eosinophilic granulocytes. The results indicate that thymic hormones or T cells or both can stimulate granulopoiesis. They apparently play no indispensable role in short-term leucopoiesis, however, since their influence was weak in our experimental models. Consequently, marked effects seen in vitro in simplified cellular systems may lose some importance in the more complex in vivo setting.